Change in visual acuity and associated risk factors after trabeculectomy with adjunctive mitomycin C

Purpose To report the 5-year incidence of visual impairment after mitomycin C-augmented trabeculectomy (MMC trabeculectomy) and the risk factors for visual impairment. Methods This is a multicentre prospective observational cohort study. Among glaucoma patients registered in the Collaborative Bleb-related Infection Incidence and Treatment Study performed in Japan, the patients with eyes meeting the following qualifications were included: eyes with primary open-angle glaucoma; eyes with primary angle-closure glaucoma; eyes with exfoliative glaucoma; eyes with ≥3/60 in blindness analysis; and eyes with ≥20/60 in low-vision analysis and visual acuity loss analysis. The patients were followed at 6-month intervals for 5 years. The entry data and follow-up data were analysed to determine the incidence of blindness (<3/60), low vision (≥3/60 and <20/60) and visual acuity loss (≥0.2 logMAR) during the follow-up period. Risk factors for visual impairment were also analysed. Results A total of 694 eyes of 694 or 559 eyes of 559 glaucoma patients were subjected to the blindness analysis or the low-vision and visual acuity loss analysis, respectively. Visual acuity significantly deteriorated (p < 0.0001): 12.2% (95%CI: 9.8–14.7%) of the patients became blind; 12.1% (95%CI: 9.4–14.9%) were judged to have low vision at the final examination; 28.3% (95%CI: 24.5–32.0%) were judged to have visual acuity loss. Glaucoma subtypes, poor preoperative visual function and postoperative complications are the main risk factors for visual impairment. Conclusions Visual acuity was significantly reduced after MMC trabeculectomy in 5 years, and we identified several risk factors associated with this complication.